DICOM PS3.3 2020e - Information Object Definitions
C.8.8.15.15 Source Model ID

The Source Model ID (300A,021B) ties together the physical source properties. The creator of the plan has used this ID to select the radioactive source model for the plan. An example would be the name of the used TG-43 data.

DICOM PS3.3 2020e - Information Object Definitions